This invention relates to a bar code reader having an electronic stylus.
Optical readers, such as bar code readers, are now quite common. Typically, a bar code comprises a series of encoded symbols, and each symbol consists of a series of light and dark regions, typically in the form of rectangles. The widths of the dark regions, the bars, and/or the widths of the light spaces between the bars indicate the encoded information.
A bar code reader illuminates the code and senses light reflected from the code to detect the widths and spacings of the code symbols and derive the encoded data. Bar code reading type data input systems improve the efficiency and accuracy of data input for a wide variety of applications. The ease of data input in such systems facilitates more frequent and detailed data input, for example, to provide efficient inventories, tracking of work in progress, etc. To achieve these advantages, however, users or employees must be willing to consistently use the bar code readers. The readers therefore must be easy and convenient to operate.
A variety of scanning devices is known. One particularly advantageous type of reader is an optical scanner which scans a beam of light, such as a laser beam, across the symbols. Laser scanner systems and components of the type exemplified by U.S. Pat. No. 4,387,297 and U.S. Pat. No. 4,760,248xe2x80x94which are owned by the assignee of the instant invention and are incorporated by reference hereinxe2x80x94have generally been designed to read indicia having parts of different light reflectivity, e.g., bar code symbols, particularly of the Universal Product Code (UPC) type, at a certain working range or reading distance from a hand-held or stationary scanner.
FIG. 1 illustrates an example of a prior art bar code reader unit 10 implemented as a gun shaped device, having a pistol-grip type of handle 53. A lightweight plastic housing 55 contains the laser light source 46, the detector 58, the optics and signal processing circuitry and the CPU 40, as well as a power source or battery 62. A light-transmissive window 56 in the front end of the housing 55 allows the outgoing light beam 51 to exit and the incoming reflected light 52 to enter. The user aims the reader 10 at a bar code symbol 70 from a position in which the reader 10 is spaced from the symbol, i.e., not touching the symbol or moving across the symbol.
As further depicted in FIG. 1, the reader 10 may include a suitable lens 57 (or multiple lens system) to focus the scanned beam into a scanning spot at an appropriate reference plane. A light source 46, such as a semiconductor laser diode, introduces a light beam into the axis of the lens 57, and the beam passes through a partially-silvered mirror 47 and other lenses or beam-shaping structures as needed. The beam is reflected from an oscillating mirror 59 which is coupled to a scanning motor 60 energized when the trigger 54 is pulled. The oscillation of the mirror 59 causes the reflected beam 51 to scan back and forth in a desired pattern.
A variety of mirror and motor configurations can be used to move the beam in a desired scanning pattern. For example, U.S. Pat. No. 4,251,798 discloses a rotating polygon having a planar mirror at each side, each mirror tracing a scan line across the symbol. U.S. Pat. No. 4,387,297 and U.S. Pat. No. 4,409,470 both employ a planar mirror which is repetitively and reciprocally driven in alternate circumferential directions about a drive shaft on which the mirror is mounted. U.S. Pat. No. 4,816,660 discloses a multi-mirror construction composed of a generally concave mirror portion and a generally planar mirror portion. The multi-mirror construction is repetitively reciprocally driven in alternate circumferential directions about a drive shaft on which the multi-mirror construction is mounted.
The light 52 reflected back by the symbol 70 passes back through the window 56 for application to the detector 58. In the exemplary reader 10 shown in FIG. 1, the reflected light reflects off of mirror 59 and partially-silvered mirror 47 and impacts on the light sensitive detector 58. The detector 58 produces an analog signal proportional to the intensity of the reflected light 52.
A digitizer circuit mounted on board 61 processes the analog signal from detector 58 to produce a pulse signal where the widths and spacings between the pulses correspond to the widths of the bars and the spacings between the bars. The digitizer serves as an edge detector or wave shaper circuit, and the threshold value set by the digitizer determines what points of the analog signal represent bar edges. The pulse signal from the digitizer is applied to a decoder, typically a programmed microprocessor 40 which will have associated program memory and random access data memory. The microprocessor decoder 40 first determines the pulse widths and spacings of the signal from the digitizer. The decoder then analyzes the widths and spacings to find and decode a legitimate bar code message. This includes analysis to recognize legitimate characters and sequences, as defined by the appropriate code standard. This may also include an initial recognition of the particular standard the scanned symbol conforms to. This recognition of the standard is typically referred to as autodiscrimination.
To scan a symbol 70, a user aims the bar code reader unit 10 and operates movable trigger switch 54 to activate the light beam 51, the scanning motor 60 and the detector circuitry. If the scanning beam is visible, the operator can see the scan pattern on the surface on which the symbol appears and adjust aiming of the reader 10 accordingly. If the light produced by the source 46 is marginally visible, an aiming light may be included in the optical system. The aiming light, if needed, produces a visible light spot which may be fixed, or scanned just like the laser beam; the user employs this visible light to aim the reader unit at the symbol before pulling the trigger.
The reader 10 may also function as a portable computer terminal. If so, the bar code reader 10 would include a keyboard 48 and a display 49, such as described in the previously noted U.S. Pat. No. 4,409,470.
In optical scanners of the type discussed above, the laser diode, the lens, the mirror and the means to oscillate the mirror all add size and weight to the handheld scanner. The photodetector and the associated processing circuitry also add size and weight. In applications involving protracted use, a large heavy handheld unit can produce fatigue. When use of the scanner produces fatigue or is in some other way inconvenient, the user is reluctant to operate the scanner. Any reluctance to consistently use the scanner defeats the data gathering purposes for which bar code systems are intended. Also, a need exists for small scanner units to fit into small compact devices, such as notebooks.
Thus, an ongoing objective of bar code reader development is to miniaturize the bar code reader as much as possible, and a need still exists to further reduce the size and weight of the scan unit and to provide a particularly convenient scanner system. The mass of the moving components should be as low as possible to minimize the power required to produce the scanning movement and to facilitate operation at high scanning speeds.
It is also desirable to modularize scanning components, so that a particular module can be used in a variety of different scanners. A need exists, however, to develop a particularly small, lightweight module which contains all necessary scanner components.
Smaller size scanning components tend to operate at higher scanning frequencies. In typical bar code scanning applications, however, the scanning frequency of the moving spot should be relatively low, typically 20 Hz or less. If the frequency increases, the speed of the spot as it passes over the indicia increases. The signals produced by the detector also increases in frequency, and consequently the bandwidth of the processing circuitry for analyzing the detector signals must be increased. Also, operation at higher scanning frequencies generally produces detector signals which include higher levels of noise, making accurate decoding more difficult.
Another series of problems has arisen in scanning bar codes which are difficult to read. Many bar codes are printed using relatively low quality printing techniques because the cost of printing such codes is low. The resultant bar codes, however, often include a number of printing defects. Also, even though printed without defects, bar code labels often become worn or damaged over time so that substantial portions of such codes become unreadable. Existing moving spot scanners produce a single scan line which remains stationary over the portion of the code at which the operator aims the scanner. If the scanned portion of the bar code contains one or more defects, the scanner typically cannot obtain a valid reading of the code. The defect may or may not be sufficiently evident so that an operator can recognize the defect and aim the scanner at a portion of the code which contains no defects. If the operator tries repeatedly to scan the code, by chance the operator may aim the scanner at a section of the code free of defects and obtain a valid read result. The need to repeatedly scan the code, at times for no apparent reason, tends to frustrate the operator and slows down data gathering operations requiring scanning of large numbers of codes. Although explained in terms of scanning defective or damaged codes, similar problems arise in scanning particularly small codes. Clearly, a need exists to develop a scanner which can extract valid information from small indicia and/or intact portions of bar codes or similar indicia having optical defects.
Further problems arise from association of the optical reader with other devices connected to a common computer system. In actual use, the device for reading optically encoded information typically connects to some form of computer. Often a need exists for entry of other data, in addition to that scanned by the optical reader. For example, in an inventory system using bar code readers, the operator scans an item and then enters the quantity of such items presently in stock. Consequently, in most systems using optical readers of the type discussed above, the system will include additional data entry devices coupled to the same computer. Separate data entry devices, however, are often in convenient to carry along in conjunction with a portable optical reading device. Also, the use of multiple data input devices requires use of several of the optional card slots of the computer and additional physical wiring connections. Furthermore, multiple input devices often create software problems directing the multiple data input streams to a single application program running on the computer.
To alleviate these problems, a number of optical readers incorporate a keyboard and an alphanumeric display to form an integrated data entry terminal. These integrated terminals have included both contact wand type bar code readers and pistol grip type moving spot scanners. The data entry capabilities of such integrated terminals, however, have been limited by the nature of the keyboard and display.
A number of other types of data entry devices is known, and in many applications provide more convenient or xe2x80x9cuser friendlyxe2x80x9d data entry operation than do keyboards and alphanumeric displays. For example, a mouse allows a computer operator to move a cursor to point at an option illustrated on a display screen. The operator then xe2x80x9cclicksxe2x80x9d a button on the mouse to select the particular option. The mouse can also provide graphical data input. U.S. Pat. No. 4,906,843 to Jones, et al., discloses a combination mouse and optical scanner, but the optical scanner scans characters or graphics data, not optically encoded information such as bar codes. The user manually scans characters by moving the mouse across the surface on which the characters appear.
A number of other keyboardless, data entry terminals has been proposed. U.S. Pat. No. 4,972,496 to Sklarew, for example, discloses a terminal device having a flat transparent input screen for generating input information when an operator contacts the screen with a stylus. A display screen mounted below the input screen displays symbols and graphic information drawn by the stylus. The operator inputs information into the associated computer through pen strokes essentially as if writing on a tablet with a pen. U.S. Pat. No. 4,916,441 to Gombrich discloses a handheld terminal including a non-contact point source type bar code reader and a touch sensitive display screen.
From the above discussion, it should be clear that a need still exists to further develop various computer input devices integrated with means to scan optically encoded indicia which also provide convenient operation.
One objective of this invention is to provide a bar code reader which is more convenient and efficient to use when reading encoded information.
Another objective of the present invention is to provide an integrated data entry terminal for optically reading encoded information and for convenient input of other forms of data.
More specifically, one objective is to combine a bar code reader with a display and touch sensitive type data entry terminal, particularly where the bar code reader is a moving spot scanner.
It is an objective to incorporate a bar code reader, for example, the moving spot scanner, and the stylus of a graphic data input device into a single handheld instrument.
The invention permits incorporation of a beam scanning module and an electronic stylus for input of positional data to a digitizer tablet or computer touch screen. In this aspect, the invention includes a pen shaped housing having a tapered tip at one end, an enlarged section at an end opposite the tapered tip, and an elongated body between the ends. A beam scanner module is located in the enlarged section of the pen shaped housing. This module emits a beam of light and directs the beam of light along a light path extending along an outer surface of the body of the pen shaped housing toward a target surface on which optically encoded indicia appears. The stylus may also include a writing nib mounted in the tapered tip of the pen shaped housing.
In the preferred embodiment, this electronic stylus provides positional data inputs to the digitizer/screen upon contact of the tip of the pen shaped housing to a surface of the digitizer/screen. A photodetector is mounted in the pen shaped housing, for sensing light reflected from the optically encoded indicia and producing an electrical signal representative of variations of light reflectivity of the optically encoded indicia. A manually actuatable switch permits the operator to activate the beam scanner module to initiate reading of the optically encoded indicia. The switch is mounted on a side surface of the body of the pen out of said light path at a point near the tapered tip. Consequently, the operator can activate the switch using the thumb or forefinger without obstructing the light path.